PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-1 Life expectancy: Not specified Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hemoglobin at least 10.0 g/dL No underlying disease associated with active bleeding Hepatic: Bilirubin no greater than 1.5 mg/dL AST less than 3 times upper limit of normal (ULN) (5 times ULN in the presence of liver metastases) Renal: Creatinine no greater than 1.5 mg/dL Other: No active infection requiring therapy No other malignancy within the past 5 years except carcinoma in situ of the cervix or nonmelanoma skin cancer Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception